Absorption refrigeration



Feb. 2 1953 c. A. MILLER ET AL 2,629,234

ABSORPTION REFRIGERATION Filed Dec. 8, 1947 Patentecl Feb. 24, 1953 UNITED STATES PATENT ()FFICE ABSORPTION REFRIGERATION Charles A. Miller, Victor G. Dreier, and William Gilchrist, Evansville, Ind., assignors to Servel, Inc., New York, N. Y., a corporation of Delaware Application December 8, 1947, Serial No. 790,368

Claims, (01. c2 11e.5)

This invention relates to refrigeration and particularly to absorption refrigerating systems of the three-fluid or uniform pressure type.

In absorption refrigerating systems of the uniform pres-sure type wherein the evaporator or cooling element includes a low-temperature or freezing section and a high-temperature or box cooling section, and wherein liquid refrigerant flows from the condenser first into the lowtemperature section of the evaporator and from there into the high-temperature section, and wherein inert pressure-equalizing gas flows first in c-ounterflow relation with liquid refrigerant in the low-temperature section of the evaporator and from there into the high-temperature section, it is highly desirable that the liquid refrigerant en route from the condenser to the lowtemperature section of the evaporator be precooled before entering the said low-temperature section. The precooling of liquid refrigerant en route from the condenser to the low-temperature section of the evaporator increases the efficiency of the refrigerating system, permits the low-temperature section of the evaporator to operate at lower temperatures and results in a more uniform temperature across the low-temperature section of the evaporator.

It is an object of this invention to provide an improved means for precooling liquid refrigerant en route from the condenser to the low-temperature evaporator of a refrigerating system of the above type.

In accordance with this invention, a precooler is provided for liquid refrigerant en route from the condenser to the low-temperature section of the evaporator wherein the conduit flowing such liquid refrigerant is placed in good thermal contact with a conduit that flows cold rich inert gas from the outlet of the high-temperature section of the evaporator to a gas heat exchanger. This conduit which flows cold rich inert gas is provided with means, such as a helical insert, discs or the like, for increasing the length of the path of flow of such gas therethrough. Furthermore, any liquid refrigerant that flows from the outlet of the high-temperature section of the evaporator, which refrigerant would otherwise be more or less wasted, is evaporated and diffused into the rich inert gas flowing in the conduit between the outlet of the high-temperature section of the evaporator and the gas heat exchanger. In this manner, an additional refrigerating effect is produced and further cooling of the liquid refrigerant en route from the condenser in the low:

temperature section of the evaporator is effected.

2 The invention together with the above and other objects and advantages will be more clear- 1y understood from the following detailed description and accompanying drawing wherein:

Fig. 1 is a view diagrammatically illustrating a refrigerating system incorporating this inven- 1011.

Fig. 2 is a side elevational view, partly in longitudinal section of a detail of this invention.

Fig. 3 is a transverse vertical sectional view taken substantially on line 3-3 of Fig. 2:.

Referring to Fig. 1, for purposes of illustration, the invention has been incorporated in a uniform pressure type absorption refrigerating system, which system includes generally, a generator it, a condenser ll, evaporator I2, an absorber l3 and conduits interconnecting said elements for flow of a refrigerating medium, an absorption liquid and an inert pressure-equalizing gas. The system may be charged, for example, with a refrigerant-absorbent solution, wherein ammonia may be the refrigerant and water the absorbent, and with hydrogen as the pressure-equalizing as. 9

The generator l0 comprises a substantially horizontal shell divided into a strong solution chamber I 4 and a weak solution chamber l5, which latter chamber is provided with an upright portion or standpipe l6. Chamber I 4 is provided with a dome H. A riser or vapor-lift conduit 18 is connected between chamber l4 and the upper part of standpipe l6. As shown, the lower end of conduit 18 extends downward into dome I! of chamber I4. The generator is heated byany suitable means, such as a gas burner 19 arranged so that the flame therefrom is projected into the lower portion of a flue 20, which flue projects concentrically through the shell of the generator. The upper end of standpipe H, is connected by a conduit 22 to the lower end of an analyzer 23. The upper or vapor outlet end of the analyzer is connected by a conduit 24 to the upper or inlet end of condenser II. The outlet end of the condenser is connected by a relatively large'conduit 25 and a small conduit 26 to the refrigerant inlet end of a low-temperature section l2 of the evaporator. The refrigerant outlet end of section 12 of the evaporator is connected by a drain conduit l2 to a high-temperature section [2 of the evaporator.

Weak solution chamber l5 of the generator is connected by a conduit '21, a conduit 28, a conduit 29 forming the inner passage of a liquid heat exchanger 30, and a [conduit 3i to the upper part of section It of the absorbers As shown. a portion of conduit 21 passes through the analyzer and conduit 28 is connected to the vapor conduit 22 leaving the standpipe. The lower part of section i3 of the absorber is connected by a conduit 32 to section l3 of the absorber. The lower or liquid outlet end of the absorber is connected by an absorber vessel 33, a conduit 33, a conduit 35 which forms the outer passage of liquid heat exchanger 30, a conduit 36, the analyzer 23, and a conduit 3'! to the rich solution chamber 14 of the generator.

The lower portion of section 13* of the absorber is connected by a conduit 38, an outer passage 39 of a gas heat exchanger 40, and a conduit 4| to the inert gas inlet end of section i2 of the evaporator. The inert gas outlet end of section 12 of the evaporator :is connected by a, conduit 42 to the inert gas inlet end of section l2 of the evaporator. The inert gas outlet end of section 12 of the evaporator is connected by a conduit 43, an inner passage 44 of the gas heat exchanger, a conduit 45, and absorber vessel 33 to the lower or gas inlet end of the ab.- sorber. A pressure vessel 46 is connected at its upper end to conduit 25 by conduit 47, and at its lower end the pressure vessel i connected .to the absorber vessel by a conduit 48.

In accordance with this invention, and-a .best shown in Figs. 2 and 3, conduit 26 which conveys liquid refrigerant from the condenser to 10W- temperature section 12 of the evaporator is placed in good thermal contact, as by welding, soldering .01 the like, toiconduit 43 which conveys cold inert ga from high-temperature section 12 of the evaporator .to the gas heat exchanger. The portion :of conduit 43 that is arranged in heat transfer relation with conduit 26 .is provided with a helical'insert 4.9. .Asshownbest in Fig.3, the lower portion of conduit 43 is distorted .101 drawn out .ofround so that achannel Si) is .provided between the lower'part of the helicalrinsert and the inner bottom surface :of conduit :43.

:In operation, heat applied :to the flue 2i! vof the generator causes expulsion of refrigerant vapor from solution therein. Refrigerant vapor .i -expelled from solution in both strong solution chamber 14 and weak solution chamber 15. Refrigerant vapor expelled .from solution .in strong soluticnchamber .1 4 collects in the-dome :H .and passes therefrom into and through vapor-lift conduit 1 .8, liftingabsorption solution therewith into the upper part of standpipe 16. The :refrigerant vapor that passes into standpipe it from the vapor-lift .conduit, along with the vapor that passes from-weaksolution chamber I 5 through the standpipe, flows from the upper part' of the standpipethrough conduit 22 into the lower end of analyzer 23. In the-analyzer the refrigerant vapor flows upward in counterflow relation with rich absorption solution thatenters the upper part thereof through conduit 36, and

tion I2 of the evaporator through conduit 42 into section I2 of the evaporator wherein the inert gas flows in concurrent relation with liquid refrigerant which enters this section of the evaporator through drain conduit 12 The cold rich mixture of inert ga and refrigerant vapor flows from the lower or outlet end of section 12" of the evaporator through conduit 43 into the inner passage of the gas heat exchanger, and from there the rich inert gas flows through conduit 45, and absorber vessel 33 into the lower or gas inlet end of the absorber.

Absorption solution weak in refrigerant flows into the upper part of section I3 of the absorber wherein this absorption solution flows in concurrent relation with inert gas and tends to push the inert gas toward conduit 38. In this manner, the direction of flow of inert gas is started and maintained in the proper direction in the inert gas circuit. The absorption solution flows from the lower end of section 13 ofgthe absorber through conduit 32 into the next lower section i3, and from there the absorption ,solution 'iiows countercurrent to inert ,gas flowing upward through the absorber, whereby the refrigerant vapor is absorbed into the absorption solution and'the inert gas stripped of refrigerant vapor flows from the gas outlet end of the absorber through conduit 38, outer passage 39 of the gas heat exchanger, and conduit 41 back to section E2 of the evaporator.

The absorption solution 'rich -in refrigerant vapor flows from the lower part {of the absorber into absorber vessel 33, and from ihfire the enriched absorption solution flows through conduit 34, outer passage 35 of the liquid heat exchanger, conduittt, analyzer 23, and conduit 3'! back to the strong solution chamber I4 of the generator. In the generator refrigerant vapor is expelled from solution and absorption solution is lifted through vapor-lift pump 18 by vapor lift action tostandpipe it, a explained above. Absorption solution weak in refrigerant flOWS from weak solution chamber 55 through conduit 21, conduit 28,-inner passage 29 of theliquid heat exchanger, and conduit 3% back to the section {3 of the absorber.

The liquid refrigerant flowing from the condenseren route to section 12 of the evaporator in passing-through conduit 26; is cooled by trans.- fer of heat'from the warm liquidrefrigerantto the cold rich inert gas flowing through conduit 43 from the outlet of section 12 of-the evaporator to the ga heatexchanger. Thehelical insert '49 in conduit43'causes the cold richigasto sweep againstthe inside walls of conduit 43, thereby improving the heat transfer between the warm liquid in conduit 26 and-the coldgas in conduit .43. For purposes of illustration, the-channel 50, shown in Fig.2 is exaggerated.

That portionof conduit 43 that is inheat exchange relation with conduit 26 issubstantially horizontal, so that any liquid refrigerant that flowsfrom the outlet of section 12 of theevaporator .into this conduitforms ashallowpool of such liquid in the channel-Wat the bottom of this conduit. This liquid refrigerant is evaporated byheat picked up fromthe liquid refrigerant flowingthrough conduitifi en routeto the low-temperature section of the evaporator and the refrigerant vapor resulting from such evaporation diffusesinto the inertgasthatris caused to pass over the surface of the liquid refrigerant by. the helical. insert, thereby producing van addi. tional refrigerating. effect for preceding the liquid refrigerant. Any excess liquid that passes through conduit 43, which with our improved precooler will be mostly absorption liquid that may have been carried into the evaporator with liquid refrigerant, is conveyed through trap 5| into the inner passage of the gas heat exchanger. The Width of the ribbon of metal of which the helical insert 49 is formed is but slightly less than the inside diameter of conduit 43, so that when this conduit is drawn out of round at the bottom portion thereof the helical insert fits rather snugly within this conduit, except for the shallow channel 50 that is formed in the bottom of the conduit. With this arrangement no additional means is required for holding the helical insert in proper position within the conduit, and no particular skill is required in fabricating the precooler. The arrows'in Fig. 3 show that the helical insert 49 fits snugly Within more than the upper half of conduit 43.

Having thus disclosed our invention, we wish it understood that we do not desire to be limited to the specific structure illustrated and described, for obvious modifications may occur to a person skilled in the art.

What is claimed is:

1. A refrigerating system including a conduit for flow of liquid and gas therethrough, said conduit comprising a generally round tube, and a helical insert in said tube for lengthening the path of flow of gas therethrough, said tube being distorted sufliciently out of round to form a shallow channel throughout the length of the tube beneath said helical insert, the latter being formed to fit within said tube above said channel in any degree of rotation of the insert relative to the tube.

2. An absorption refrigerating system of the continuous cycle inert gas type including an evaporator having a low-temperature section and a high-temperature section connected for series flow of liquid refrigerant and inert gas, an absorber, a gas heat exchanger, gas conduits connecting said evaporator and absorber and gas heat exchanger in a circuit for inert gas, a conduit for conducting liquid refrigerant to the lowtemperature section of the evaporator, said liquid conduit being in thermal contact with one of said gas conduits in the path of flow of inert gas from the high-temperature section of the evaporator to the gas heat exchanger, and means in said gas conduit for lengthening the path of flow of inert gas therethrough.

3. A refrigerating system as set forth in claim 2 in which said gas conduit is provided with a channel for flow of liquid lengthwise thereof below said means for lengthening the path of gas flow.

4. A refrigerating system as set forth in claim 2 in which said gas conduit is a generally round tube distorted sufiiciently out of round to form a shallow channel running the length of the tube beneath said means for lengthening the path of gas fiow.

5. A refrigerating system as set forth in claim 2 in which said gas conduit is a generally round tube, and said means for lengthening the path of gas flow is a helical insert, said tube being distorted sufficiently out of round to form a shallow channel running the length of the tube beneath the helical insert.

CHARLES A. MILLER.

VICTOR G. DREIE-R.

WILLIAM GILCHRIST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,849,685 Munters Mar. 15, 1932 2,059,877 Kogel Nov. 3, 1936 2,167,663 Lyford Aug. 1, 1939 2,321,113 Taylor June 8, 1943 2,363,399 Coons Nov. 21, 1944 FOREIGN PATENTS Number Country Date 486,268 Great Britain June 1, 1938 537,999 Great Britain July 16, 1941 

